In the summer, after I had applied sun block on myself, I listened to a CD. While fumbling the CD case, I must have left some greasy block on my fingers that had transferred itself to the CD case. It made the case go all cloudy and I’ve tried practically everything to get it off, water just bounces right off it (obviously.) In the end I just gave up and swopped CD cases. It was my fave CD aswell! grrr
Some of the components in sunblock will mar the surface of plastics. I think the label has a warning of this type.
Re your case why not just snap it apart and transfer the front and back paper cover inserts to another clear and perfect CD case? If you’re careful they snap apart and back together easily.